A moist wound closure is known in the prior art (Blank, Wundversorgung und Verbandwechsel, Kohlhammer-Verlag, Stuttgart, 2001; Stalick, Br J Nurs 2004, 13(18):1107-1109; Metzger, Home Health Nurse 2004, 22(9):586-590). The problem with this type of wound treatment is that the contact medium, for example, bandage gauze, plaster, etc., may concrete with the wound during the heal-over process. As the contact medium is subsequently removed, the wound is frequently reopened, which results in the destruction and removal of the newly generated tissue. Clearly, the wound healing process is unnecessarily slowed down as a result. When using wound dressing pads that do not adhere to the wound, thereby preventing concretion of the dressing pad with the wound, the wound defect nevertheless lacks a support and guide structure to which the newly formed tissue is oriented and on which it can grow. This condition leads, particularly in the case of deep wounds, to the formation of a substantive defect. A further consequence is the formation of unnecessary and undesirable scarring. In clinical practice, this problem extends to all wounds that involve not only the epidermis, but the corium as well and, where applicable, the subcutis (so-called “deep” wounds), and requires reconstitution of both the epidermal layers, the corium and, where applicable, the subcutis.
The thickness of the epidermis (upper dermal layer) normally varies and, depending upon location, can measure from 0.03 to 4 mm. Age and sex influence the thickness of the epidermis as well. The epidermis contains no blood vessels, and is formed from keratinocytes. Keratinocytes are horn cells which possess a cell nucleus and which produce keratic material, or keratin. Keratin is water repellant and imparts resiliency to the skin tissue.
The underlying corium is a resilient layer of skin tissue containing a high ratio of loosely intertwining connective tissue. This layer may also vary in thickness, depending upon location. On the penis and eyelids the corium is a mere 0.3 mm in thickness, whereas on the hands and soles of the feet, it can measure as much as 2.4 mm.
The aforementioned problems concern both slow-healing or completely non-healing wounds, such as the chronic diabetic-neuropathic ulcus, ulcus cruris, decubitus wounds and secondary healing wounds, as well as non-irritating, primary healing wounds (for example, ablative lacerations, excoriations (in which tissue has been grazed and thereby removed from the wound), and split thickness removal sites.
Biologically degradable and/or resorbable fiber structures (silicon gel-fibers and fiber structures) are known from German patent application DE-C 196 09 551 (incorporated herein in its entirety by reference). These fiber structures are obtained by drawing fibers from a spun composition and optionally drying them. The spun composition contains one or more partially or completely hydrolytically condensed silicon compounds derived by hydrolytic condensation of monomers of the general formula SiX4, wherein residues X1, X2, X3, and X4 are identical or different and are either hydroxyl, hydrogen, halogen, amino, alkoxy, alkyloxy, alkylcarbonyl or alkoxycarbonyl, or are derived from alkyl-residues and can be interrupted by one or more oxygen atoms, sulfur atoms or amino groups.
Methods for producing a skin tissue graft and/or cells, tissues and organs based on the aforementioned fibrous structures are also known from WO 01/42428 and EP-A 01 262 542. PCT publication WO 01/42428 (incorporated herein in its entirety by reference) describes a method for producing a skin tissue graft, in particular a skin tissue autograft, wherein skin tissue cells are placed on the surface of a culture medium and allowed to grow. This method is characterized in that a surface element, in particular an aforementioned biocompatible, biodegradable and/or bioresorbable fiber, webbing or fabric is placed on the culture medium along with the skin tissue cells. The fibers of the surface element have a diameter ranging from about 5 μm to about 20 μm. The term “about” as used herein means approximately and refers to a range of values of plus or minus 10% of a specified value. For example, the phrase “about 20 μm” includes plus or minus 10% of 20 μm, or from 18 μm to 22 μm.
EP patent application EP-A 01 262 542 (incorporated herein in its entirety by reference) describes a method for the in vitro production of cells, tissues and organs, in which the fiber matrix (see, DE-C 196 09 511) functions as a cell support substance and/or guide structure for the extra-cellular matrix formed by the cells, and makes it possible for the cells to find a spatial orientation which permits the cells to multiply and/or to achieve their genetically determined differentiation.
Realizing the limitations and shortcomings of the prior art described above and the need for a better contact medium for accelerated wound healing, the present invention describes the developing and preparing of a contact medium, in its broadest sense a dressing, gauze, plaster, capable of contacting a wound, but without having to tolerate the aforementioned disadvantages such as concretion of the contact medium and the wound, destruction of newly formed tissue, unnecessarily slow wound healing, excessive scarring, and defective (healing) growth. Thus, the present invention provides a contact medium, in particular a multilayer bandage, for which it is possible to leave the contact medium in or on a moist wound and to leave it in place even after the wound has healed over, so as to not disrupt the healing process, to provide a guide structure for the newly forming tissue, and lastly to prevent the formation of scarring.